Under Pressure

30 December, 2007

In 1965 the Venera 3 space probe crashed into Venus. It was the first spacecraft to arrive on another planet, and even though it failed to return any useful data the Soviets would follow this mission with many more, some of which would survive the tremendous difficulties in landing on the surface of the Hell that is Venus. Long associated in ancient cultures with beauty, Venus was the planet that finally brought the evidence that showed that the geocentric view of the solar system (with the earth in the centre) had to be wrong. Galileo saw the varying phases of Venus through his telescope and this observation matched the prediction of the Copernican system and proved incorrect the old geocentric idea. At the dawn of the telescope age Venus was adding to our scientific knowledge. But alas, even as telescopes improved, Venus remained mysterious due to it being entirely and continually covered in clouds. This lead some to speculate in the early 20th century that Venus was a swamp filled world possibly similar to the ancient Earth with giant lizards roaming it’s steamy plains. With the 1960’s space probes, humanity inched forward to peer at Venus.

Many of the probes failed but along with radar imaging from Earth these probes gathered more data and our view of Venus changed. Thanks to it’s cloud cover and a runaway greenhouse effect the surface temperature of Venus is on average 480 °C, and the pressure is over 90 times that on Earth. If you were standing on the surface you would be crushed and boiled at the same time. Oh yes, and it rains sulfuric acid. Small wonder that it took immense engineering skill to finally get spacecraft to land on Venus. But unlike the robotic probes on Mars which often lasted for many years longer than expected, no Venusian lander survived long in those harsh conditions. Probe lifetimes were measured in hours, not months. In 1990 the spacecraft Magellan arrived at Venus and sat in orbit around this devastating planet. Sitting safely above the clouds Magellan used radar imaging to map 98% of the planet over four years before plunging into the atmosphere and finding a hot and squishy death.

Now that we have maps of Venus we can see that there are no lush jungles, no large dinosaurs walking the swamps of a sister planet. But the developments in technology required to send probes into high pressure areas that occurred in the 1960’s and 70’s did not just help with Venus. Here on Earth there were unexplored places where pressure was proving a problem. The ocean deeps would crush any normal submarine and specially designed explorers were needed to journey to the crushing depths away from the continental shelves. Hundreds of metres below the surface, the ocean floor does not have the abundance of life of shallower waters due to the lack of sunlight. Plants cannot exist that deep and so many of the animals live off debris from dead creatures that float down from above. The ocean deep looked to be a desert, until a startling discovery was made near the Galapagos Islands.

In the deep sea, where no light can reach, thermal vents called Black Smokers were found. Superheated water breaks through the Earth’s crust bringing rich sulfide minerals, and extreme temperatures. The water was 400 °C, and would have boiled were it not for the immense pressure. The water was acidic, and yet here, there was an abundance of life. Bacteria which thrived on the heat and sulfides were the basis for a mini eco system that had no need of the sun at all. The bacteria was incorporated into clams, and sea worms. Blind fish patrolled the darkened depths, enough food here for shoals. At the same time as we discovered that Venus looked to be uninhabitable, we discovered that one of the most inhospitable places on Earth, hot and under pressure, was teeming with life.